Field of the Disclosure
The present disclosure relates generally to wireless communication systems and, more particularly, to access nodes in wireless communication systems.
Description of the Related Art
Wireless communication systems provide wireless connectivity using a network of base stations that provide coverage to large-scale (or macrocellular) coverage areas. The base stations are typically connected to the network using reliable, but costly, high bandwidth wired connections such as fiber-optic cables. However, macrocellular base stations are not the most efficient way to provide coverage to dense urban environments because the complex topology creates significant fading. Macrocellular coverage may therefore be supplemented by other access nodes (which may be referred to as “small cells”) that may be mounted on light poles, telephone poles, or the sides of buildings to provide high data rate coverage to outdoor users such as pedestrians walking on the street. Installing wired connections to connect small cells to the network may be very costly. Consequently, the small cells are typically connected to the macrocellular base stations using non-line-of-sight (NLOS) wireless backhaul connections to provide the backhaul connection to a macrocellular base station.
A conventional NLOS wireless backhaul connection includes a set of backhaul connectors that are connected to the small cells. Each small cell is connected to a backhaul connector over a digital interface such as a common public radio interface (CPRI) or Ethernet interface. The backhaul connector forms NLOS wireless backhaul connections with other backhaul connectors (connected to other small cells) or the macrocellular base station. Signals exchanged between the small cell and the backhaul connector must be down-converted to baseband, processed by a high-resolution analog-to-digital converter to generate digital I/Q baseband signals for transmission over the digital interface, and/or further processed by a baseband unit or modem. Signals received by the small cell or the backhaul connector over the digital interface must be processed by a digital-to-analog converter to generate the baseband signal, which is then up-converted to the appropriate radiofrequency for transmission over an air interface by the small cell or the backhaul connector.